void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(D1, OUTPUT);
  pinMode(D2, OUTPUT);
  pinMode(D3, OUTPUT);
  pinMode(D4, OUTPUT);
  
}

void loop() {
digitalWrite(D1, HIGH);
delay(200);
digitalWrite(D2, HIGH);
delay(200);
digitalWrite(D3, HIGH);
delay(200);
digitalWrite(D4, HIGH);
delay(200);
digitalWrite(D1, LOW);
digitalWrite(D2, LOW);
digitalWrite(D3, LOW);
digitalWrite(D4, LOW);
delay(200);
}